Apparatus and method for programming a projectile

ABSTRACT

A measurement apparatus is provided, which is included on a measurement and programming basis for a projectile, which detects the fields and/or signals which emerge/originate from a programming coil, and is electrically connected to an evaluation device which itself evaluates these detected values. These values can then be taken into account for the programming of the projectile.

This nonprovisional application is a continuation of InternationalApplication No. PCT/EP2012/055531, which was filed on Mar. 28, 2012, andwhich claims priority to German Patent Application No. DE 10 2011 018248.9, which was filed in Germany on Apr. 19, 2011, and which are bothherein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for measurement ofelectromagnetic fields on and/or within a programming device which, forexample, is included on the muzzle of a tube weapon, in particularhaving a measurement apparatus on a programming device for an air burstmunition (ABM), that is to say having a field test appliance on ameasurement and programming basis. The measurement apparatus can measurefields and/or signals from the programming coil, thus making it possibleto check the correct operation of the programming coil, the programmingsignal and the time correlation with the projectile, as well as theprogramming of a projectile itself. In special cases, these values canthen be taken into account for the programming of the projectile.

2. Description of the Background Art

The term a tube weapon can denote both guns and rocket launch tubes. Theterm projectile is intended to mean all airborne vehicles which can belaunched or fired from a weapon barrel, that is to say ballisticprojectiles and projectiles which at least partially propel themselves.The term ballistic projectiles means normal conventional projectileswhich detonate on impact, such as projectiles which can be fuzed and/orprogrammed, and, for example, detonate in flight. The projectiles may bespin-stabilized and/or fin-stabilized and may, for example, be in theform of discarding sabot projectiles, primary projectiles which carry aplurality of secondary projectiles in them, or exercise projectiles witha core and casing.

In general gunnery, the muzzle velocity of a projectile is normallyreferred to as V₀, and is also referred as the V₀ velocity. This istherefore the velocity at which a projectile launched or fired from atube weapon moves on its trajectory relative to the weapon barrel whenit emerges from the weapon barrel. The flight duration, the firingdistance and the hit-point position are dependent, inter alia, on the V₀velocity. However, precise knowledge of the muzzle velocity V₀ isparticularly important in the context of programmable projectiles, sincethe time at which a programming code is transmitted to a projectile inorder to achieve the desired weapon effect depends on the muzzlevelocity, V₀. The muzzle velocity V₀ also depends on the weight and thetemperature of the propellant charge.

A theoretical muzzle velocity V₀(theor.) can be determined bycalculation if all the relevant data relating to the weapon, the weaponbarrel and the projectile to be fired or launched is known. However, themuzzle velocity V₀ differs from the theoretically calculated muzzlevelocity V₀(theor.). In addition, the V₀ velocity is reduced as aconsequence of weapon barrel wear. Therefore, the actual muzzle velocityis preferably in each case measured on firing, in order to correct theazimuth and elevation of the weapon barrel as necessary for the targetto be attacked, and/or in order to appropriately program the projectile,or at least the subsequent projectiles.

An airburst munition (ABM) is a munition type which breaks up during theflight phase without any need to strike a target object or to be in thevicinity of a target object. For this purpose, a suitable mechanism isused to fire a break-up charge within this munition and to cause it toexplode. If the muzzle velocity of the ABM is known sufficientlyaccurately, the desired range can be determined via an indication of atime after which the break-up charge is intended to be fired afterleaving the muzzle. Because of the natural scatter in the muzzlevelocities of ABM, it is particularly important, for this type ofmunition, to determine the initial velocity at the muzzle (V₀) withsufficient accuracy.

Various apparatuses and methods are known for measurement of the actualV₀ velocity. Frequently, the measurement of the V₀ velocity is based ona gate principle. A V₀ measurement such as this is known from EP 0 108973 B1, which corresponds to U.S. Pat. No. 4,677,376. In this case, twocoils are used, which are arranged at a known distance from one another,to be precise after the exit cross section of the weapon barrel, seen inthe direction of flight of the projectile. These coils and the distancebetween them form a measurement base path. The coils are in generalarranged at least approximately concentrically with respect to thelongitudinal axis of the weapon barrel, and their internal diameter issomewhat larger than the calibre of the weapon barrel. The coils areconnected to current sources, thus resulting in a magnetic field in thearea of each coil, and an induced voltage can be tapped off as theprojectile passes through. While a projectile is flying through the areaof the coils, the magnetic field is disturbed, and the voltage which canbe tapped off changes as a function of the relative position of theprojectile with respect to the coil. CH 691 143 A5 deals with the samesubject.

Therefore, if the V₀ of the individual projectile is determined at themuzzle of the gun, then, after the appropriate break-up time has beencalculated, this value can be programmed into the projectile via aprogramming unit, which is located downstream in the direction of theprojectile flight path, as a result of which the projectile is broken upby the break-up charge at the desired point. One such system is known,for example, from EP 0 802 390 A1 (which corresponds to U.S. Pat. No.5,814,755), EP 0 802 392 A1 (which corresponds to U.S. Pat. No.5,814,756) and EP 0 802 391 A1 (which corresponds to U.S. Pat. No.5,834,675), which are all herein incorporated by reference. In thiscase, the projectile passes through a measurement path in the area ofthe muzzle, which measurement path is formed by two coils arranged onebehind the other, and produces a time-dependent voltage signal in eachof these coils. If the distance between the coils is known, theprojectile velocity can be determined from these signals. Theappropriate break-up time is calculated in a computation unit, and isprogrammed in the projectile via a third coil.

In order to make it possible to set the time fuzes for breaking up theprojectile with the desired accuracy, it is necessary, according to theteaching of EP 0 467 055 A1, which corresponds to U.S. Pat. No.5,117,732, which is incorporated herein by reference, to transmit atleast 12 bits from the transmission coil of the programming device tothe receiving coil in the projectile. By way of example, in the case ofa muzzle velocity of 1200 m/s, the receiving coil in the projectilepasses by the transmission coil, which is attached to the weapon barrelmuzzle, in a relatively short time, as a result of which only a shorttime is available for transmission of the information from thetransmission coil to the receiving coil. At the same time, thetransmission time window must be chosen such that the projectile islocated within the transmission coil at that time.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide anapparatus which can be used for accurate programming while a shot isbeing fired.

In an embodiment, the invention is based on the idea of checking thecorrect operation of the programming coil, the programming signal andthe time correlation with the projectile as well as the programming of aprojectile itself. This can be done by detection of the fields and/orsignals of the programming coil. This information can then be taken intoaccount in the programming. The measurement apparatus according to theinvention furthermore makes it possible to also detect disturbancefields from further components of the tube weapon, as well asdisturbance fields which act on the tube weapon from the outside.Furthermore, it is also possible to check for active incident radiationfrom, for example, Natel, radar, active jamming devices and switchingjammers. These are further influences which can now be taken intoaccount during programming. Admittedly, test devices which can detectfields and signals of a programming coil are already known, for exampleby the term base test appliance, but these are restricted to laboratoryenvironments, that is to say they do not measure the situation of a realshot, and the possible correction associated therewith.

In order to implement the idea within the scope of an existingprogramming device, for example in the area of the muzzle of a tubeweapon and preferably even on the programming coil for the munitionitself, an additional measurement apparatus is provided, that isindependent of the programming coil, can detect the signals which arepresent in the area of the programming coil, and in particular thesignals emitted by the programming coil, and can pass these to ameasurement evaluation device. The system is designed as a purelypassive system.

In the simplest case, this measurement apparatus may have a coil havingone or more turns around the muzzle opening of the tube weapon. The coilis functionally connected to a fundamentally known signal receiving andsignal processing device, for example via a wire connection.

The coil can be positioned such that, on the one hand, it does not coverthe unobstructed opening of the barrel muzzle, while nevertheless at thesame time makes it possible to detect sufficiently well the fields whichemerge/originate from the programming coil with a low field strength.For this purpose, they must be positioned outside the metallic screeningof the programming coil.

The number of coil turns may be one or more. Since the number of turnsinfluences the response time of the coil, the turns are chosen on thebasis of the flank gradient of the signal to be detected. The fastestresponse behaviour is achieved with a single coil winding. Better signalsensitivities are achieved with a plurality of windings—the bestsolution should in each case be chosen depending on the signal strengthand the gradient. The windings may either be in the form of wire in asurrounding structure or, alternatively and particularly preferably, maybe implemented in the form of a printed circuit board (“print”).

An electrically non-conductive material should be provided for thematerial surrounding the coil, for example non-conductive plastics orepoxy materials. At the same time, it is advantageous for this materialto have low density, which therefore means only a small additional massin the area of the muzzle since, as is known, additional masses in themuzzle area influence the dynamic and static behaviour of the tubeweapon.

The measurement apparatus can be attached to the programming coilassembly via an adhesive joint, a push joint or else as a printedembodiment on a surface. The positioning can be considered in many ways.

This results, inter alia, in the further advantages of a good signalevaluation capability: bit patterns and possible interruptions, signalstrengths, attenuations and single-bit tests, that is to say whethercorrect bits have been set. Furthermore, the time window/time instant ofprogramming (within 20 μs) can be tested, and the programming basis canbe tested during actual firing. An independent functional and qualitytest of the programming base can also be carried out. This is used as areferee tool for failure (to break up in the intended targetregion): >caused in the programming, or in the munition?< and thedocumentation of the base characteristics during acceptance firing.

A measurement apparatus is proposed which is included on a measurementand programming basis for the programming of a projectile (13), whichcan detect the fields and/or signals which emerge/originate from aprogramming coil. These “detected” values are evaluated in an evaluationdevice, and can then also be made available for programming theprojectile. This therefore makes it possible not only to make decisionson the method of operation of the programming coil as such, but also toimplement corrections, when this is electronically possible.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus, are not limitiveof the present invention, and wherein:

FIG. 1 shows a longitudinal section through a measurement andprogramming device according to the conventional art,

FIG. 2 shows a sectional illustration of an embodiment of a measurementapparatus for measurement of the field and/or of the signals of at leastthe coil of the programming device,

FIG. 3 shows a sectional illustration of an embodiment,

FIG. 4 shows a sectional illustration of an embodiment, and

FIG. 5 shows a sectional illustration of an embodiment.

DETAILED DESCRIPTION

FIG. 1 shows a supporting tube 20, which is attached according to theprior art to the muzzle of a gun barrel 13 and includes three parts 21,22, 23. Annular coils 24, 25 for the measurement of the projectilevelocity are arranged between the first part 21 and the second and/orthird parts 22, 23. A transmission coil 27, which is held in a coilformer 26, is attached to the third part 23—also referred to as theprogramming part. Lines 28, 29 are provided for feeding the annularcoils. Soft-iron bars 30 are arranged on the circumference of thesupporting tube 20, for screening against magnetic fields whichinterfere with the measurement. The projectile 18 has a receiving coil31, which is connected to a time fuse 34 via a filter 32 and a counter33. When the projectile 18 passes through the two annular coils 24, 25,a pulse is produced at short successive intervals in each annular coil.These pulses are fed to an evaluation circuit (not illustrated), inwhich the projectile velocity is calculated from the time intervalbetween the pulses and the distance a between the annular coils 24, 25.The projectile velocity is used to calculate a break-up time, which istransmitted inductively to the receiving coil 31 in a suitable formwhile the projectile 18 is passing through the transmission coil 27, inorder to set the counter 32 etc.

FIG. 2 describes a first embodiment of the apparatus 10 according to theinvention. In this case, this section drawing represents the muzzle 11of the tube weapon, which is formed by a component 1 which extends in acircular form around the barrel centre axis 2. At least one winding 5 ofthe measurement apparatus 10 is incorporated within an electricallynon-conductive attachment ring 4. The ring 4 is preferably adhesivelybonded to the end surface of the tube-weapon muzzle, and in the processisolates the winding 5 from the electrically conductive closure cap 3 onthe tube weapon.

FIG. 3 describes a second embodiment of the apparatus 10′ according tothe invention. In this case, this section drawing represents the muzzle11 of the tube weapon, which is formed by the component 1 which extendsin a circular shape around the barrel centre axis 2. At least onewinding 5 of the measurement apparatus 10 is incorporated within anelectrically non-conductive attachment ring 12. The ring 12 is equippedwith an enlarged area, in order to improve the adhesive joint to thecomponent 1 and the closure cap 3 on the tube weapon.

FIG. 4 describes a third embodiment of the apparatus according to theinvention. In this case, the attachment ring 14 is in the form of a capwhich can be placed over the muzzle 10 of the tube weapon. This improvesthe mechanical retention of the measurement apparatus 5 according to theinvention on the tube weapon further in comparison to the previousembodiments.

FIG. 5 describes a fourth, particularly preferred, embodiment of theapparatus according to the invention. In this case, a conductor track 5′in the form of a circular coil winding is provided as a printed circuitwithin the attachment ring 15, with electrical connecting component 6being passed out of the attachment ring 15, and being operativelyconnected to an evaluation device 16.

The additional measurement apparatus 10, which is preferably included inthe area of the programming coil 27, is used to detect the emittedsignals from the transmission or programming coil 27, and to pass themto the evaluation device 16. The result or results can then also beincluded in the programming of the projectile 13 (correction). In anycase, information relating to the method of operation of the programmingcoil 27 can be derived.

It is self-evident that this principle may also be used for testing themeasurement coils 24, 25, although the design complexity is undoubtedlygreater here than that for testing the programming coil 27.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are to beincluded within the scope of the following claims.

1. An apparatus for programming a programmable projectile, the apparatuscomprising: at least one programming coil; and a measurement apparatusconfigured to detect fields and/or signals which emerge/originate fromthe programming coil and is electrically connected to an evaluationdevice, which evaluates these detected values.
 2. The apparatusaccording to claim 1, wherein the detected values are made available ascorrection values for the programming of the projectile.
 3. Theapparatus according to claim 1, wherein the measurement apparatus has acoil with one or more turns around a muzzle opening of a tube weapon. 4.The apparatus according to claim 1, further comprising a conductor trackconfigured as a circuit coil winding, and wherein the measurementapparatus is a printed circuit.
 5. The apparatus according to claim 1,wherein the measurement apparatus located such that it does not coverthe unobstructed opening of the barrel muzzle.
 6. The apparatusaccording to claim 1, wherein the measurement apparatus is included inan attachment ring that is configured to be adhesively bonded to an endsurface of a tube-weapon muzzle.
 7. The apparatus according to claim 6,wherein the attachment ring is equipped with an enlarged area.
 8. Theapparatus according to claim 6, wherein the attachment ring is a cap. 9.A method for programming a programmable projectile, the methodcomprising: providing at least one programming coil; providing ameasurement apparatus that detects fields and/or signals whichemerge/originate from the programming coil; and evaluating the detectedfields and/or signals in an evaluation device.
 10. The method accordingto claim 9, wherein the values are made available as correction valuesfor the programming of the projectile.